I had two years of a guy reading vaguely towards the class from a maths book, hoping every pupil could instantly get everything and not bother him with questions. Then switched to a lovely lady who actually engaged with the class and went through the process and concept of things step by step - leaving the main gist up on the board while setting exercises.

I suddenly became really good at maths within a few months of starting with her.

I'm generally crap with maths anyway but I wasn't helped along in any way just half an hour to an hour of bullshit and kids throwing kids over tables some days (in the names of shits and giggles). Better at English but that was all self taught more than lessons.